I. Field of the Invention
The present invention relates to the maintenance of sufficient water depth in harbors and navigation channels. More specifically, the present invention relates to an improved apparatus for scouring and resuspending sediments transported in the waterway by natural currents.
II. Background Art
The present invention is an improvement of a buoyant wing disclosed in applicant's copending U.S. patent application Ser. No. 513,865, filed July 14, 1983 entitled "Method and Apparatus for Impeding Sediment Deposition in Harbors and Navigational Channels", now U.S. Pat. No. 4,560,304 issued Dec. 24, 1985, the disclosure being incorporated by reference herein. The wing disclosed in the previous application was configured as a buoyant high aspect ratio delta wing having an inverted airfoil shape for producing a downward lift force when anchored at a negative angle of attack adjacent the bottom of the waterway having a current. The net vertical deflection and turbulant trailing wake generated as the water flows past the wing prevents sediments from depositing on the bottom of the waterway for a predetermined distance downstream of the wing. Cascading arrays of the wings may be anchored in succession along the waterway to scour and resuspend sediments and thereby maintain sufficient water depth for navigation while avoiding the cost of environmental drawbacks of dredging. The buoyant high aspect ratio delta wings are generally constructed of a urethane foam injected into a steel reinforced concrete mold. The urethane foam has a high density, such as 16 pounds per cubic foot, and may be poured into a partition section of the mold to create a spanwise extending wing spar in the thickest portion of the hydrofoil cross section. The remainder of the wing may be made of urethane foam having a lower density such as 2 pounds per cubic foot. The wing is typically covered with resin impregnated fiberglass. The foam used is typically sufficient to withstand the pressure encountered underwater without deformation. A wing with a 20 foot wingspan generally creates 600 pounds of useable lift while displacing up to 2500 pounds of water. As a result, the wing would need to be ballasted to approximately 1900 pounds dry weight to maintain 600 pound of net buoyancy. To achieve the 1900 pounds of ballasted weight results in the need to use excess materials.
It is therefore an object of the present invention to provide a new and improved wing profile which produces increased wing turbulance and high lift when mounted adjacent the bottom of a waterway having a current for resuspending sediments or scouring the bottom of the waterway.
It is yet another object of the present invention to provide a wing profile which has a reduced displacement volume and reduced structural weight while providing high lift and increased turbulance.